Org-mode 9 was just released, and it changed the syntax for export blocks. I need to change:

#+begin_html
…
#+end_html

to

#+begin_export html
…
#+end_export

The org-mode changes file includes some elisp to change this. However, I couldn't get it to work, and I also wanted to change all my files, not run this elisp on one file at a time. Here are the commands I ran:

Idea: when at at Chinese restaurant, use facial recognition and/or tap into vast databases of personal information linked to your credit card to gather lots of information about the people at the table, then use deep neural networks to write a custom fortune for each person, then use focused microwaves to print these on blank pieces of heat-sensitive paper embedded inside fortune cookies. Then when you get your fortune cookie, it'll be personalized just for you. Maybe it could be a targeted ad!